Panning Provider doesn't quite fully attentuate left/right audio

When I try to shift the audio balance between the left and right speaker, I don't seem to fully get rid of the audio from the side that is not supposed to get any audio. There seems to be a bleed effect of sorts to the opposite speaker.

I still do hear the balance shift between the left and right speaker and I do see that the array element for the speaker not getting audio is set to 0.

Just wondering if this could be a sound card issue or perhaps poor headphones that have some sort of cross-over issues.

The pan strategy should have a multiplier for 0 for right channel if you pan all the way left. So if the audio coming out of the PanningSampleProvider is correctly zeroing all the right-hand samples, then it must be something strange going on with the
playback.
Try feeding the panned audio into a WAV file and looking in Audacity or an audio file editor to check that your panning really is silencing one channel.